Using Computational Fluid Dynamics to investigate the generation of soluble bedrock forms

Abstract:

The roles and interactions of processes that generate bedforms in soluble bedrock settings are not yet fully understood. One outstanding puzzle is the morphogenesis of scallops. Current chemical theory does not allow dissolution rate to spatially vary under many of the conditions at which scallops are thought to form. This lack of variation in dissolution rate disagrees with the creation and existence of scallops for a large portion of the range of scallop sizes that are found in nature. Previous studies that have examined processes that generate bedforms using computational fluid dynamics (CFD) have made simplifying assumptions to ensure tractability. Consequently, tractability is sacrificed and some fine scale effects associated with the driving processes are not modeled. We incorporate Large-Eddy Simulation (LES) and adaptive meshing into a lattice-Boltzmann CFD method for fluid flow, chemical dissolution, and solute transport allowing relaxation of simplifying assumptions employed in previous models. These methods can model sub-grid scale turbulence and resolve the dissolution and precipitation processes occurring at the fluid-solid interface. We use this CFD model to simulate flow and dissolution over scallops and flutes to investigate the formational processes responsible for variations in dissolution rate that drive the spatio-temporal evolution of these features.